<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
/*
if(表达式){
    //代码
}


 */
//var f = false
var num = 0
if(num == 0){
    console.log("你好")
}
</script>
</body>
</html>